This proposal is directed toward the initiation of three independent research projects in psychobiology and aging. The first project will examine spatial memory in aged rats. In particular, the project will attempt to relate changes in spatial memory to alterations in hippocampal electrophysiology. The second project will examine sympatho-adrenal activity in aged rats in response to acute and chronic stress. These experiments examine plasma catecholamine concentrations at various times before and after the stress procedures. In addition, the experiments examine other measures of stress responses, including blood pressure, defection, and gross motor activity. The third project involves development of an animal model to examine the possibility that the rapid forgetting in aged animals may reflect alterations in neuroendocrine responses to training. The research plan includes examinations of the effects, on retention performance, of subcutaneous injections of several hormones (e.g., epinephrine, norepinephrine, and ACTH) administered shortly after training or before retention tests.